Herein disclosed are imaging members, such as layered photoreceptor structures, and processes for making and using the same. The imaging members can be used in electrophotographic, electrostatographic, xerographic and like devices, including printers, copiers, scanners, facsimilies, and including digital, image-on-image, and like devices. More particularly, in embodiments there is disclosed a photoreceptor that exhibits excellent ghosting characteristics due primarily, it is believed, to the property of the photoreceptor exhibiting little or no response to a known number of injected positive charges at for example, a specific time after injection and processes for testing the photoreceptor attributes to thereby control, minimize, or eliminate paper edging and ghosting. More specifically there is disclosed processes for identifying photoreceptors which are encompassed by the testing methods disclosed and photoreceptors which are not encompassed by the testing methods disclosed to thus arrive at photoreceptors with desirable properties with improved performance as compared for example, to photoreceptors which are not encompassed by the aforemtioned testing methods.
Electrophotographic imaging members, e.g., photoreceptors, include a photoconductive layer formed on an electrically conductive substrate. The photoconductive layer is an insulator in the substantial absence of light so that electric charges are retained on its surface. Upon exposure to light, charge is generated by the photoactive layer, and under applied field charge moves through the photoreceptor and the charge is dissipated.
In electrophotography, such as xerography, electrophotographic imaging or electrostatographic imaging, the surface of an electrophotographic plate, drum, belt or the like, imaging member or photoreceptor, containing a photoconductive insulating layer on a conductive layer is first uniformly electrostatically charged. The imaging member is then exposed to a pattern of activating electromagnetic radiation, such as light. Charge generated by the photoactive layer move under the force of the applied field. The movement of the charge through the photoreceptor selectively dissipates the charge on the illuminated areas of the photoconductive insulating layer while leaving behind an electrostatic latent image. This electrostatic latent image may then be developed to form a visible image by depositing charged particles of same or opposite polarity on the surface of the photoconductive insulating layer. The resulting visible image may then be transferred from the imaging member directly or indirectly, such as by a transfer member, to a print substrate, such as a transparency or paper. The imaging process may be repeated many times with reusable imaging members.
An electrophotographic imaging member may be provided in a number of forms. For example, the imaging member may be a homogeneous layer of a single material such as vitreous selenium or it may be a composite layer containing a photoconductor and another material. In addition, the imaging member may be layered. These layers can be in any order, and sometimes can be combined in a single or mixed layer.
Multilayered photoreceptors have at least two layers, and may include a substrate, a conductive layer, an optional charge blocking layer, an optional adhesive layer, a photogenerating layer, sometimes referred to as a “charge generation layer,” “charge generating layer,” or “charge generator layer”, a charge transport layer, an optional overcoating layer and, in some belt embodiments, an anticurl backing layer. In the multilayer configuration, the active layers of the photoreceptor are the charge generation layer (CGL) and the charge transport layer (CTL). Enhancement of charge transport across these layers provide better photoreceptor performance.
The demand for improved print quality in xerographic reproduction is increasing. Common print quality issues are strongly dependent on the quality of the different photoreceptor layers. A common problem includes “ghosting,” which is thought to result from the accumulation of charge somewhere in the photoreceptor. Consequently, when a sequential image is printed, the accumulated charge results in image density changes in the current printed image that reveals the previously printed image. Thus, there is a need, which is addressed herein, for a way to minimize or eliminate charge accumulation or consequences thereof such as release of charge accumulation in photoreceptors in the sequential printed images and/or identify the photoreceptors which have such capability.
The terms “charge blocking layer” and “blocking layer” are generally used interchangeably with the phrase “undercoat layer.”
Photoreceptors and their materials are disclosed in Katayama et al., U.S. Pat. No. 5,489,496; Yashiki, U.S. Pat. No. 4,579,801; Yashiki, U.S. Pat. No. 4,518,669; Seki et al., U.S. Pat. No. 4,775,605; Kawahara, U.S. Pat. No. 5,656,407; Markovics et al., U.S. Pat. No. 5,641,599; Monbaliu et al., U.S. Pat. No. 5,344,734; Terrell et al., U.S. Pat. No. 5,721,080; and Yoshihara, U.S. Pat. No. 5,017,449, which are herein incorporated by reference in their entirety.
Additional photoreceptors are disclosed in Fuller et al., U.S. Pat. No. 6,200,716; Maty et al., U.S. Pat. No. 6,180,309; Dinh et al., U.S. Pat. No. 6,207,334; U.S. Publication No. 2007/0292793; and U.S. Publication No. 2007/0292784, which are herein incorporated by reference in their entirety.